Mobile navigation and location-tracking systems are commonly included on mobile computing devices such as smartphones. For example, a mobile computing device may be used to guide a user between locations using, for example, global positioning system (GPS) circuitry on the mobile computing device and referencing a geographical map. However, such systems are frequently limited to outdoor applications due to a need for network and/or GPS connectivity. Indoor navigation and location tracking solutions oftentimes track the location of the mobile computing device without relying on GPS and/or external sensors.
Mobile computing devices typically include a number of inertial sensors that collect data, which may be analyzed by, for example, an on-board inertial measurement unit (IMU) to determine various context of the user, such as the user's estimated location. “Dead reckoning” is one typical process of calculating a user's current position based on a previously determined position, estimated speed, and elapsed period of time, which may be determined based on sensor data generated by the inertial sensors. On-board inertial sensors such as accelerometers and magnetometers make it possible for mobile computing devices to count a user's steps and take compass readings for navigational purposes (i.e., for pedestrian dead reckoning). Although pedestrian dead reckoning (PDR) permits indoor navigation while consuming less power (e.g., compared to GPS navigation) and requiring less a priori information, accurately performing pedestrian dead reckoning has several challenges. For example, pockets of large magnetic distortion in buildings and/or the user's hand motion may cause typical PDR algorithm traces to be inaccurate.